Japanese health system has been evaluated to be the closest to the ideal Universal Health Coverage(UHC)in the world. "Ideal UHC" is to ensure that all people could obtain the health services they need without suffering any financial hardship. However, maintaining current healthcare system, under which all medications are covered, is getting difficult due to the aging society and the existence of high-price drugs such as anti-cancer agents. Approval of OPDIVO(nivolumab)has raised the national discussion in Japan because of the possibility that the use of OPDIVO might collapse overall healthcare system. Many countries that have public health insurance system like Japan have introduced Health Technology Assessment(HTA)for pricing and reimbursement decision. In the UK, The National Institute for Health and Care Excellence(NICE)is in charge of HTA and using health-economic data for reimbursement decisions. Japan has decided to implement HTA and the provisional phase has started this year. The use of health-economic data is different between Japan and UK. For instance, health-economic data is used only for pricing in Japan, although it is also used for reimbursement in the UK. HTA implementation in Japan has been criticized, saying that it might prohibit patients' access to medical treatments. However, the HTA is the solution of rising national burden of medical costs. It could benefit to sustainable UHC, and therefore, it could ensure patients' access to essential medicines.